Multiple plunger injection cylinder for die casting



June 2 1970 c, PARLANn ET AL MULTIPLE PLUNGER INJECTION CYLINDER FOR DIECASTING Filed April 29, 1968 States Patent OK" 3,515,203 MULTIPLEPLUNGER INJECTION CYLINDER FOR DIE CASTING Conrad A. Parlanti, Berkeley,Calif., and George H. Fashfellow, St. Charles, and Dort Fauntleroy,Geneva, 11]., assignors to Moline Malleable Iron Company, St. Charles,11]., a corporation of Illinois Filed Apr. 29, 1968, Ser. No. 724,926Int. Cl. B22d 17/10 US. Cl. 164-312 6 Claims ABSTRACT OF THE DISCLOSUREIn the die casting of molten metal, for example ferrous orhigh-temperature metals having temperatures in the range of 2600 F. to3500 F., the molten metal is introduced into an injection cylinder andthe metal is normally moved by a reciprocating plunger from theinjection cylinder into the die cavity. The extreme heat from the metalwithin the injection cylinder chamber can damage the plunger. This isovercome by having a plurality of plungers so arranged so that theplungers are sequentially positioned to be used in the injectioncylinder chamber, thus minimizing distortion and permitting each plungerto cool before it is again utilized to move molten metal.

SUMMARY OF THE INVENTION This invention relates to a die casting methodand apparatus in which a plurality of sequentially positioned plungersare used to move molten metal from a die casting injection cylinder.

Another purpose is a die casting apparatus for use with high temperaturemolten metals utilizing a plurality of sequential plungers forpreventing plunger distortion due to contact with the molten metal.

Other purposes will appear in the ensuing specification, drawings andclaims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrateddiagrammatically in the following drawings wherein:

FIG. 1 is an axial section through a die casting apparatus of the typedescribed, and

FIG. 2. is an end view of the plunger cylinder illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the die casting of hightemperature molten metals, for example in the range of 2600 F. to 3500F., it has been found that the end of the plunger which contacts themolten metal to move it into the die cavity becomes distorted. Suchdistortion can damage the plunger to the point where it will not moveWithin the injection cylinder. To overcome the problem of temperaturedistoition, we utilize a plurality of sequentially operated plungers,there being a sufficient time lapse between the use of each plunger suchthat it can cool down to a satisfactory temperature. It is thecontinuous uninterrupted use of the same plunger at high temperatureswhich causes distortion.

In FIG. 1, an injection cylinder is indicated generally at 10 and theremay be an interior chamber 12 defined by a sleeve 14. The injectioncylinder may take a variety of different forms, however, as shownherein, the cylinder is made up of laminations which are specificallydesigned to prevent temperature distortion within the injection cylinderitself. Surrounding the lamination 14 there is an intermediate layer orlamination 16 and Patented June 2, 1970 there may be an outer laminationor outer shell 18. The outer layer 18 is formed of a high strengthsteel, for example a steel having the designation H13 has been found tobe satisfactory. A beryllium copper alloy having high heat conductivityhas been found to be satisfactory for the intermediate layer 16. A heatresistant material, for example Rene 41, one of the group of metalsknown as Super Alloys, has been found to be satisfactory for the innerlayer 14. It is important that the outer layer have high strength; theintermediate layer have high heat conductivity; and the inner layer havea high degree of heat resistance.

Because temperature distortion is not only a problem with the face ofthe plunger, but it is also a problem in the injection cylinder itself,it is desired in some applications to heat the injection cylinder to atemperature approximating that of the temperature inside of the chamber12 when there is metal in it. For example, a plurality of axiallyextending electric rods 20 may be positioned within the intermediatelayer 16. These rods are effective to bring the interior of theinjection cylinder or the chamber 12 up to a temperature such that theintroduction of molten metal into the chamber will not cause non-lineartemperature distortion.

The invention should not be limited to an injection cylinder which isheated by any particular means. For example, heating coils may be woundaround the injection cylinder, or there may be an injection cylinderwhich is heated by hot gases. What is important is to preventtemperature distortion of the injection cylinder.

In like manner, the invention should not be limited to an injectioncylinder which is heated. In some applications, cooling fins whichextend radially out from the injection cylinder may be utilized torapidly dissipate the additional heat added to the injection cylinder bythe introduction of molten metal therein. In such instances, temperaturedistortion is minimized. and, to a large extent, eliminated by the rapiddissipation of heat from the injection cylinder.

It is important to have some means in the injection cylinder foreliminating non-linear temperature distortion. Otherwise, although theplunger may have means for compensating for high temperatures, it canstill cause damage to the injection cylinder if the temperature of theinjection cylinder is not itself also stabilized.

The injection cylinder 10 may have an open end 22 which has directaccess to a die cavity. The cover side of the die is indicated at 24 andmay be suitably attached to a platen 26 by means of a platen adapter orthe like 28. The details of the die and the attachment of the die to theinjection cylinder are not important. What is important is to provide adie casting injection cylinder which can readily introduce molten metaldirectly into the die cavity. The injection cylinder may be completed bya molten metal feed passage 3(l which opens into the chamber 12 at theend of the chamber away from the open end 22.

A cylinder is indicated generally at 32 and may include a plurality ofaxially extending passages 34. Within each of the passages 34 is aplunger 36. Each of the plungers is of a size and is so arranged thatWhen it is in axial alignment with the chamber 12, it may be operated todrive molten metal within the chamber 12 into the die cavity. Themechanism for actually operating the plungers may be conventional andmay be of the general type used with the single plunger arrangements nowin use in injection cylinders. At the center of the cylinder 22 is ashaft 38 about which the cylinder rotates. The mechanism for rotatingthe cylinder 32 may be conventional. One requirement is that the timingof the rotation of the injection cylinder 32. be coordinated with 3 theintroduction of molten metal through the passage 30 into the chamber 12.

At the far right-hand side of FIG. 1 the plungers are all mounted in asupport member 40. In normal operation, each of the plungers will beindividually operated by suitable hydraulic, pneumatic, or othersatisfactory operating means. As illustrated particularly in FIG. 2,there are a plurality of plungers 36 arranged in a circular orcylindrical alignment. As the cylinder 32 rotated about its shaft 38, orabout its axis, the plungers 36 will sequentially be positioned for usein the injection cylinder. By having a plurality of plungers, it ispossible for each of the plungers to cool down before the sequentialoperation will require the use of that particular plunger again.

The invention should not be limited to any particular arrangement formoving the sequentially positioned plungers. What is important is toprovide a plurality of plungers, which can be used in sequence, andmeans for moving the plungers so that their sequential operation isassured. The particular makeup of the plunger is not important, nor isits size or shape. The invention is particularly directed to eliminatingtemperature distortion at the end 42 of the plunger which is actually incontact with the molten metal when the plunger is within the injectioncylinder.

As mentioned above, the means for eliminating temperature distortion ofthe injection cylinder itself may vary. The injection cylinder may beheated to provide a crucible effect. In other applications, theinjection cylinder may be rapidly cooled by the use of radiating fins,again to eliminate temperature distortion.

Whereas the preferred form of the invention has been shown and describedherein, it should be realized that there are many modifications,substitutions and alterations thereto Within the scope of the followingclaims.

What is claimed is:

1. In a system for die casting molten metal, a mold having an inputopening, an injection cylinder positioned adjacent said mold, anopen-ended chamber in said injection cylinder, a molten metal feedpassage opening into said chamber, one open end of said chamber being inalignment with said mold input opening, a plurality of injectioncylinder plungers, carrier means supporting said plungers and adaptedfor positioning one of said plungers at the other open end of saidchamber for use in injecting molten metal from the chamber into themold, and means supporting said carrier means and adapted for movingsaid plurality of plungers, as a group, for positioning differentplungers at the other open end of said chamber.

2. The structure of claim 1 further characteriezd in that said carriermeans is a rotatable cylinder.

3. The stucture of claim 2 further characterized in that said supportingmeans has an axis offset from the axis of said injection cylinderchamber.

4. The structure of claim 1 further characterized in that said moltenmetal feed passage is adjacent the other open end of said chamber.

5. The structure of claim 1 further characterized in that saidsupporting means adapted for moving said plungers is effective tosequentially position said plungers at the other open end of thechamber.

6. The structure of claim 1 further characterized by and including meansfor reducing temperature distortion of the injection cylinder.

References Cited UNITED STATES PATENTS 2,610,372 9/1952 Schroeder.

2,748,933 6/1956 Deutsch.

2,961,705 11/1960 Wacker 18-30 3,153,815 10/1964 Seidl 183O ROBERT D.BALDWIN, Primary Examiner US. Cl. X.R.

